The present invention relates to a phosphorus-containing compound useful as additives (in particular, flame retardants, plasticizers, stabilizers, etc) for various materials (e.g., compositions including hot-melt adhesives, thermosensitive tackifiers, delayed tack adhesives, image-receiving materials for forming an image by thermal transfer, photosensitizers for color photography, meltable inks for ink jet, shock-absorbing materials, pencil leads, and so on), further for organic compounds, particularly organic polymer compounds (e.g., vinyl chloride resins), lubricants, and heat transfer medium, etc, and relates to a process for producing the same. The phosphorous-containing compound is particularly useful as flame retardants, plasticizers, stabilizers, and the like.
Conventionally, organic polymers are molded or formed, with adding additives such as flame retardant, stabilizer in order to impart flame retardancy and stability to the organic polymers. Such additives are exemplified inorganic compounds, phosphorus-containing compounds (e.g., aromatic phosphoric esters (phosphates), phosphorus-containing aliphatic condensed compounds), halogen-containing compounds (e.g., organic halogen compounds, halogen-containing organic phosphorus compound). Among these additives, the halogen-containing compounds can impart high flame retardancy. Typical halogen-containing compounds include, for example, tetrabromo-diphenylether, tetrabromo-bisphenol A, tri(dichloropropyl)phosphate, and tri(dibromopropyl)phosphate.
The halogen-containing compounds are, however, thermally decomposed under a resin-molding process to generate a hydrogen halide, and so the hydrogen halide not only corrodes a metal mold and deteriorates characteristics of resins but also causes the working environment worse. Further, poisoned gases (hydrogen halides) generated by combustion of the halogen-containing compounds affect human bodies and environments adversely.
Meanwhile, among non-halogenous series additives, since inorganic compounds such as metal hydroxide (e.g., magnesium hydroxide, aluminum hydroxide) and metal oxide (e.g., antimony oxide, alumina) have a low flame retardability, large amount of inorganic compounds is required in order to obtain a desired flame retardancy. Therefore, the properties of resin are liable to be deteriorated.
Moreover, as non-halogenous additives expressing relatively high flame-retardantability, aromatic phosphoric esters (phosphates) such as triphenylphosphate (hereinafter, occasionally abbreviated as TPP) and tricresylphosphate are used. In particular, since TPP shows excellent flame retardancy, TPP is generally used. However, the volatility of TPP is high, and TPP is volatilized in a resin composition-molding process, to contaminate metal with deteriorating the external appearance of the molded articles.
Further, even though the above mentioned halogen-series additives and non-halogen-series additives are used in combination, flame-retardability of the articles is still insufficient.
Incidentally, Japanese Patent Publication No. 19858/1976 (JP-51-19858B), Japanese Patent Publication No. 18336/1990 (JP-2-18336B) and Japanese Patent Application Laid-Open No. 1079/1993 (JP-5-1079A) disclose condensed organic phosphorus compounds having low volatility in order to enhance flame retardancy for a variety of resins (e.g., polyester resins, polyamide resins, polycarbonate resins). Particularly, Japanese Patent Publication No. 19858/1976 (JP-51-19858B) discloses a method of producing the condensed phosphate mentioned above by reacting arylenediol and diarylphosphochloridate. However, although heat resistance of these condensed phosphates is more excellent than that of TPP, it is difficult to impart high flame retardancy to resins.
Incidentally, Japanese Patent Application Laid-Open No. 55947/1982 (JP-57-55947A) discloses a halogen-containing resin composition obtained by adding a salt of organic acid with zinc, a salt of organic acid with Group IIa metal, an epoxy compound and/or an organic phosphate compound, and a specific organic phosphate compound to a halogen-containing resin, which is excellent in stability (particularly, stability of weather resistance). As the organic phosphate compounds, there are disclosed phosphoric esters (phosphates) of divalent or trivalent alcohols. The divalent or trivalent alcohols include ethylene glycol, triethylene glycol, cyclohexanediol, 1,4-phenyldimethanol, hydrogenated bisphenol.
Moreover, bicyclo phosphate compounds are disclosed in many publication, for example, ORGANIC PHOSPHOROUS COMPOUNDS vol. 6 (a Division of John Wiley and Sons. Inc.). Further, Japanese Patent Publication No. 14072/1991 (JP-3-14072B), Japanese Patent Application Laid-Open No. 35833/1999 (JP-11-35833A), Japanese Patent Application Laid-Open No. 286910/1997 (JP-9-286910A) and Japanese Patent Application Laid-Open No. 187451/1986 (JP-58-187451A) also disclose a variety of bicyclo phosphate compounds, and utilization of these compounds as an additive (e.g., flame retardant) for various resins. However, the effect (e.g., flame-retardant effect) of the compounds is not sufficient yet.
It is an object of the present invention to provide a novel phosphorus-containing compound excellent in heat resistance and useful as flame retardant, plasticizer or stabilizer.
It is another object of the present invention to provide a phosphorus-containing compound having low volatility and capable of imparting high flame retardancy to resins.
It is still another object of the present invention to provide a process for producing a phosphorus-containing compound capable of imparting high flame retardancy to resins, with high yield and high purity by simple manner.
The inventors of the present invention made Intensive studies to achieve the above objects and finally found that a phosphorus-containing compound having a specific ring structure remarkably improves flame retardancy of resins and is useful as plasticizer, stabilizer, etc. The present invention was accomplished based on the above findings.
That is, the phosphorus-containing compound of the present invention is represented by the following formula (I), (II) or (III): 
wherein Z1, Z2 and Z3 are the same or different, each representing a cycloalkane ring, a cycloalkene ring, a polycyclic aliphatic hydrocarbon ring or an aromatic hydrocarbon ring, in which the rings may have a substituent; R represents a halogen atom, a hydroxyl group, a carboxyl group, a halocarboxyl(haloformyl) group, an alkyl group, an alkoxy group, an alkenyl group or an aryl group; A represents a polyvalent group corresponding to an alkane: Y1, Y2 and Y3 are the same or different, each representing xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94 or xe2x80x94NR1xe2x80x94
wherein R1 represents a hydrogen atom or an alkyl group;
k represents an integer of 1 to 6; m represents an integer of 0 to 2; n represents an integer of not less than 1; q represents an integer of 0 to 5; r represents 0 or 1; s represents an integer of 1 to 4; and
provided that when Z1 is a cyclohexane ring, q is 0, and k is 1, factor r for A is 1; when Z1 is a cyclohexane ring, q is 0, and k is 2 to 6, at least one of plural factors r for A is 1; and when Z1 is a benzene ring and k is 1, the factor r for A is 1; when Z1 is a benzene ring and k is 2 to 6, at least one of plural factors r for A is 1.
The rings Z1, Z2 and Z3 each may be an aliphatic dicyclic hydrocarbon ring (e.g., a norbornane ring) or an aliphatic tricyclic hydrocarbon ring (e.g., an adamantane ring, a tricyclo[5.2.1.02,6]decane ring), or a benzene ring. In the formula (I), the R may be a halogen atom, a hydroxyl group, a C1-4alkyl group, or a C1-4alkoxy group. The each Y1, Y2 and Y3 may represents xe2x80x94Oxe2x80x94. The k may be 1 or 2, and n may be 1, and q may be 0 to 2. The phosphorus-containing compound represented by the formula (I), (II) or (III) may be a compound represented by the following formula (Ia), (Ib), (Ic), (Id), (Ie), (If), (IIa), or (IIIa): 
wherein the following structure
{overscore (------)}
represents a single bond or a double bond; v is an integer of 0 to 2; Z2, Z3, R, Y1, Y2, Y3, k, m, n, q, r and s have the same meanings as defined above.
The present invention also includes a process for producing the phosphorus-containing compound.